My guess is the platters were physically damaged in the fall. Pray I am wrong because that's a really bad situation for data recovery. Hopefully no stray dirt or dust got in while it was open. Yeah, it's probably going to cost quite a bit with no guarantee of a full recovery.
One of those backups should be in a different location. Maybe with a trusted friend or a bank safe deposit box. If you keep two copies and there's a fire or flood then keeping both copies near each other risks all the backups getting lost or damaged.